System for connecting wind generator blade sections

ABSTRACT

The invention relates to a system for connecting wind generator blade sections, preferably for the application in the connection of blade sections ( 1, 2 ), the formation of which comprises skins ( 3 ) determining the outer aerodynamic profile, arranged on inner stringers ( 4 ) like longitudinal partitions, the connection between the sections ( 1, 2 ) being established by means of rods ( 12 ) which are included through holes ( 8 ) defined in a longitudinal direction on the inside of the skins ( 3 ) and of the stringers ( 4 ) in the sections ( 1, 2 ), with the threaded connection of said rods ( 12 ) at one end on respective elements ( 11 ) which are fitted in one of the sections ( 1 ) and the tension is tightened by means of corresponding nuts ( 14 ) which are incorporated on the other end of said rods in the other section ( 2 ).

FIELD OF THE ART

The present invention relates to the wind generator blades which areformed by composition by means of two or more longitudinal sections, forthe purpose of facilitating the construction and essentially roadtransport, proposing a system for connecting sections in theconstructive formation of the blades, whereby advantageous features forsaid function are achieved.

STATE OF THE ART

The worldwide demand for renewable energy in order to deal with climatechange and maintain an expectation of power production without dependingon non-renewable natural resources involves in a very relevant mannerwind energy, which is mostly developed by means of wind generators whichare driven by a blade rotor capturing the wind.

The development of wind generators and their application to powerproduction by means of using the wind requires, however, wind generatorswith increasingly greater rated power which are more efficient and havea lower cost per kilowatt of the power produced.

The sweep surface of the blades of the rotor receiving the action of thewind, among other aspects, is essential in the power generation by meansof said wind generators, such that one of the factors to increase thepower generation capacity is the increase in the size of the bladescapturing the action of the wind.

Exceeding a measurement of the size of the blades of the wind generatorsentails, however, a series of collateral problems because of thedifficulties that arise both in the transport aspect, due to theexisting vehicles and highway traffic regulations, and in the aspect ofthe actual constructive assembly of the wind generator, due to the typesof cranes which must be used.

Indeed, from 35 meters in length onwards, wind generator blades havelarge transport difficulties, since they require special transportmeans, which are very expensive.

To solve this problem, the solution of forming blades by means oflongitudinal sections is already known, which sections can beindependently transported for their connection at the installation siteof the wind generator and even in the constructive assembly thereof.

This involves an advantage for large blades (between 40 and 60 meters inlength) which are already demanded by the wind sector, but also for moretraditional blades (between 30 and 40 meters in length), because sincethey can be made in sections of between 15 and 20 meters in length, theycan be transported with normal means, a reduction in the transport costbeing achieved which is advantageously greater than the cost of formingthe independent sections and connecting them in the constructiveassembly of the blades.

In this sense, several systems have been developed for connecting thesections making up wind generator blades, which are formed by theconnection of longitudinal sections, such as for example the solution ofPatent ES 9901177 but the solutions known in such sense generally havedeficiencies relating to the difficulty of the assembly and to theefficiency of the securing determining the connection between thesections.

OBJECT OF THE INVENTION

According to the invention, a system for the connection between thesections making up wind generator blades is proposed, with featureswhich make the performance of the assembly and the effectiveness of theconnection advantageous.

The system of the invention is essentially provided for bladesstructurally formed by outer side blades laminated by layers ofsynthetic fibers, arranged on an inner resistant structure formed bystringers like longitudinal partitions, the aerodynamic profile of theblade being determined by means of outer skins which can extend, theythemselves defining the trailing edge of the aerodynamic profile,whereas the formation of the leading edge of said aerodynamic profile isprovided by means of a complementary part laminated in turn withsynthetic fibers.

In the connection of the sections making up the blades there is arrangeda ring determining at its front parts channels in which there are fittedwith their end edge the inner structural stringers of the bladesections, as well as the edges of the outer skins, which in the areacomprised between the inner structural stringers are formed with asection thickened towards the inside, on the inside of which, as well ason the structural stringers there are defined longitudinal holes openingout into respective hollows of the corresponding walls, the securing ofthe connection being established by means of rods which are insertedthrough the opposite longitudinal holes of the skins and of thestructural stringers of the sections to be connected, passing throughthe intermediate ring of the connections, which rods are connected in atension threaded coupling with respect to respective end elements whichare housed in the hollows into which the longitudinal holes open out.

In the sections which are connected, the hollows into which thelongitudinal holes open out are made perpendicularly from the inner partof the corresponding walls, without passing to the outer part, saidhollows having a cylindrical shape in one of the sections of theconnection, in order to fit therein a corresponding cylindrical elementprovided with a threaded transverse hole, with respect to which therespective rod of the securing of the connection of the sections iscoupled with threading, whereas in the other section of the connectionthe hollows are oblong, the incorporation of a nut being establishedtherein on the end of the corresponding rod, to carry out the actuationon said nut through the opening of the respective oblong hollow.

A securing for the connection between the blade sections is thusobtained which allows determining a resistant fastening with completeprecision by means of tightening the nuts which are arranged on the rodsof the connection, the assembly being very easy to carry out, since thesecuring rods are incorporated before the coupling in one of thesections to be connected, such that it is then only necessary to coupleby insertion the second section and tighten the tension nuts for thesecuring on the second end of the securing rods.

The incorporation of the intermediate ring in the connection furtherdetermines a protection preventing the defibration of the layers offiber in the connection edge of the outer skins of the blade sections,which prevents, in the application work of the formed blade, the forceof the wind from being able to cause a progressive deterioration ofdefibration of the skins forming the aerodynamic profile.

In addition, making the hollows for housing the outer coupling elementsof the securing rods of the connecting, at the inner part of the wallsof the sections and without passing to the outside, means that saidwalls of the sections which are connected are not very weakened, andfurthermore the outer surface remains continuous, such that theefficiency of the aerodynamic profile for the performance of the bladeis not affected.

Due to the foregoing, the system of the invention has truly advantageousfeatures, acquiring its own identity and a preferred character for thesecuring function of the sections making up wind generator blades,compared to the already known solutions for said function.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded perspective view of the structural assembly ofa wind generator blade which is made up of two longitudinal sections,with the connection of said sections according to the invention.

FIG. 2 is a perspective view of the blade of the previous figure in itsassembled form.

FIG. 3 is a detailed perspective view of a partial section of theprevious blade, the arrangement of the structural elements of itsformation being observed.

FIG. 4 is an enlarged detail of area IV indicated in FIG. 2,corresponding to the root of the blade.

FIG. 5 is an enlarged detail of area V indicated in FIG. 2,corresponding to the connection between the sections making up theblade.

FIG. 6 is an exploded perspective view of said connection area of thesections making up the blade.

FIG. 7 is a perspective view of the same connection area of the sectionsmaking up the blade, with the outer skins being transparent to observethe elements of the inside.

FIG. 8 is a detail according to segment VIII-VIII indicated in FIG. 5,the arrangement of a securing rod of the connection between the sectionsmaking up the blade being observed.

FIG. 9 is a perspective view of the structural formation of the innerframework of the sections making up the blade.

DETAILED DESCRIPTION OF THE INVENTION

The object of the invention relates to a system intended to establishthe securing for the connection between the sections making up the windgenerator blades which are formed by independent longitudinal sectionswhich can be separately transported, for the connection thereof at theconstructive assembly site of the application wind generator.

The system of the invention is provided essentially, but without alimiting character, for blades structurally formed by two outer sideskins (3) which are arranged on an inner structure formed by stringers(4) like longitudinal partitions, such that the outer skins (3)determine the aerodynamic profile of the blade, together with acomplementary part (5) defining the leading edge, the actual skins (3)forming the trailing edge by means of their prolongation until beingconnected in this edge, as observed in FIG. 3, whereas the innerstringers (4) form a framework determining, together with the skins (3)a structural box along the formation of the blade, the stringers (4)being connected on the inside by means of supports (4.1), as observed inFIG. 9. The blades thus formed can be longitudinally unitary, but withthe same structural concept of the constructive formation, they can beformed by two or more longitudinal sections intended to be connected inthe constructive assembly of the corresponding wind generator.

According to the system of the invention, the connection between twosections (1, 2) making up a blade is established by incorporating anintermediate ring (6) determining on its front faces grooves (6.1) inwhich the outer skins (3) and the inner stringers (4) of the sections(1, 2) to be connected are fitted with their end edge, as observed inFIGS. 6 to 8.

In the end part corresponding to the connection, the outer skins (3) ofthe sections (1, 2) are formed, in the area comprised between the innerstringers (4), with a thickening (7) towards the inside, longitudinalholes (8) being defined in said thickening (7), as well as in thestringers (4), which holes correspond to one another in an oppositemanner in both sections (1, 2) and which also correspond with respectivethrough holes in the intermediate ring (6).

The longitudinal holes (8) open out into corresponding sections (1, 2)in respective hollows (9, 10) made perpendicularly at the inner part ofthe walls in which said longitudinal holes (8) are defined.

In one of the blade sections, for example, the section (1), the hollows(9) into which the longitudinal holes (8) open out are cylindrical andtherein there are fitted corresponding cylindrical elements (11)provided with a threaded transverse hole (11.1) for the threadedcoupling of the end of a rod (12) which is inserted through therespective longitudinal hole (8).

In the other blade section, in this case the section (2), the hollows(10) into which the longitudinal holes (8) open out are oblong, a stopwasher (13) and a nut (14) which is incorporated on the other end of therod (12) passing through the respective longitudinal hole (8) beinghoused in each of such hollows, such that said nut (14) can be actuatedthrough the opening of the oblong hollow (10), to thereby tighten thetension of the rod (12).

In such conditions, to establish the securing for the connection betweenthe sections (1, 2), first the cylindrical elements (11) are inserted inthe hollows (9) of the section (1) and respective rods (12) areintroduced through the corresponding longitudinal holes (8), which rodsare coupled by threading on the mentioned cylindrical elements (11),whereby said rods (12) are fixed with respect to the section (1),axially projecting from the longitudinal holes (8).

Once so, the intermediate ring (6) is inserted, making the rods (12)pass through the holes of said ring (6), which is taken in untilabutting against the section (1), and in this arrangement, in order toestablish the connection of the section (2), both parts are inserted inrelation to one another, making the rods (12) be introduced through thelongitudinal holes (8) of said section (2), up to the oblong hollows(10) thereof, wherein the washers (13) and the corresponding nuts (14)are incorporated on the end of the rods (12), such that by tighteningthe nuts (14) a tension of the rods (12) ensuring the connection betweenthe sections (1) and (2) is obtained, as depicted in FIG. 8.

The hollows (9, 10) into which the longitudinal holes (8) of thesections (1, 2) open out do not pass to the outside of the outer skins(3) of the sections (1, 2), such that the aerodynamic profile of theblade is not affected by the securing of the connection and furthermore,the structural weakening due to the mentioned hollows (9, 10) does notaffect the resistance of the blade for its function. The actuation onthe tightening nuts (14) for the securing of the connection is in anycase practicable from inside the blade, since the connection of thesections (1, 2) is established in a mid-area of the blade, wherein theinner space is sufficient for the entrance of an operator.

The incorporation of the intermediate ring (6) in the connectiondetermines in turn a protection on the edge of the outer skins (3) ofthe sections (1, 2) which are connected, preventing the defibration ofsaid skins from their edges by the action of the wind in the function ofthe application work of the blade.

1.-6. (canceled)
 7. A system for connecting wind generator bladesections, comprising: a first blade section; a second blade section,each of the blade sections having skins arranged on an inner structureformed by stringers arranged as longitudinal partitions; and aconnection between the blade sections, the connection including rodswhich pass through opposing longitudinal holes of the blade sections,and elements which are fitted in one of the sections, a first end ofeach of the rods being connected to a respective one of the elements bya threaded connection, the connection further including a respective nuton a second end of each rod and practicably incorporated in the othersection, which nuts are turnable to tighten tension of the bladesections and compress the blade sections frontally against one another.8. The system for connecting wind generator blade sections according toclaim 7, wherein the elements on which the rods are threaded arecylindrical elements with a threaded transverse hole, said elementsbeing fitted in corresponding cylindrical hollows into which thelongitudinal holes of the first blade section open, the cylindricalhollows being perpendicular at an inner part of the blade section wallsin which the corresponding longitudinal holes are defined.
 9. The systemfor connecting wind generator blade sections according to claim 7,wherein the nuts which are practicably incorporated on the second end ofthe rods are housed in oblong hollows into which the longitudinal holesof the second section open, the oblong holes being made at an inner partof the blade section walls in which the corresponding longitudinal holesare defined, whereby the nuts can be actuated through the openings ofsaid oblong hollows.
 10. The system for connecting wind generator bladesections according to claim 8, wherein the cylindrical hollows aredefined in the skins of the first blade section and only penetratepartially in the thickness of the skins, without affecting an outersurface thereof.
 11. The system for connecting wind generator bladesections according to claim 9, wherein the oblong hollows are defined inthe skins of the second blade section and only penetrate partially inthe thickness of the skins, without affecting an outer surface thereof.12. The system for connecting wind generator blade sections according toclaim 8, wherein the skins of the blade sections have, in ends of theblade sections to be connected together, an area between the innerstringers with a thickening, the longitudinal holes and thecorresponding hollows being provided in the thickening.
 13. The systemfor connecting wind generator blade sections according to claim 9,wherein the skins of the blade sections have, in ends of the bladesections to be connected together, an area between the inner stringerswith a thickening, the longitudinal holes and the corresponding hollowsbeing provided in the thickening.
 14. The system for connecting windgenerator blade sections according to claim 7, and further comprising anintermediate ring arranged between the blade sections, the intermediatering having front faces with grooves in which end edges of the skins andthe inner stringers of the blade sections which are connected arefitted, said intermediate ring establishing a reinforcement thatprevents defibration of the skins from edges of the connection.